Those of us who live in places where the temperature can get as low
as 40 below zero, see a large number of ways that living things survive
the cold. Birds, insects, reptiles, amphibians, and mammals all have unique
ways of avoiding death by freezing. Most of us have never thought about
how plants survive the cold. It would seem that trees and bushes would
be especially vulnerable to freezing as they have to sit in the wind and
the elements, waiting for the thawing of spring. If you have ever seen
a barrel or a flower pot left out with water in it in the winter, you know
that they break as the water freezes and expands. There is a demonstration
I do with my physics students in which we take a solid steel ball, fill
it with water and freeze it, and the freezing water breaks the steel--just
as it will the block of your car. Why does that not happen to the trunk
of a tree or the bud of a bush?

Some plants produce chemicals that act like antifreeze. The chemicals
lower the temperature at which the water will freeze in the same way that
antifreeze keeps your radiator from freezing. Another method plants use
has been discovered by botanists at Cornell University. When the air is
warm, plants have on their surface a thin layer of water with various other
molecules mixed in. As the temperature drops, this water freezes, but the
other molecules are not included in the ice crystals. As the concentration
of these other molecules increases, water inside the plant cells is drawn
out by osmosis. This process continues until the cells in a plant bud are
almost totally dehydrated. If there is no water in the bud, the bud can
freeze without damage. In the spring when the temperature rises, water
is drawn back into the bud and the cells revive. Where we live, in the
early fall you see plants covered with what is called rime. This is the
water drawn out of the plant. It falls away and the plant is winterized.
In the spring, water can get back into the bud and start the plant working
before the ground is even thawed, giving the plant a jump on spring.

One amazing thing about plants is that they seem to be able to grow
anywhere, but that only happens because they have a design that makes them
able to survive even hostile environments. As we learn more of those designs
we have to be impressed with the wisdom and complexity of them--a testimony
to the God who created them with purpose and function in mind.